如何使用存储过程将主键值传递给C＃中的外键

Question

I'm trying to insert values into two tables using stored procedure.

This is stored procedure I've used

ALTER PROCEDURE [dbo].[insert_emp_pics]
@EmpName nvarchar(100), 
@Nationality nvarchar(30), 
@PassportPic nvarchar(100), 
@Pic nvarchar(100)
AS
Begin
set nocount on;
DECLARE @ID int, 
@Emp_ID int
insert into Employee (EmpName,Nationality)
values (@EmpName,@Nationality)
set @ID = SCOPE_IDENTITY();
insert into DatePics 
(Emp_ID,PassportPic,Pic)
values
(@Emp_ID,@PassportPic ,@Pic)
set @ID_Pics  = SCOPE_IDENTITY();
 end

And this is my C# statement

        private void Savebtn_Click_1(object sender, EventArgs e)
    {


        if (Nametxt.Text == "" || Nationalitydrp.SelectedItem == null )
        {
            nameerr.Text = ("*");
            nationalityerr.Text = ("*");

        }
        else
        {               

            SqlCommand com = new SqlCommand();                
            com.Connection = db.con;
            com.CommandType = CommandType.StoredProcedure;
            com.CommandText = "insert_emp_pics ";
            com.Parameters.AddWithValue("@EmpName", Nametxt.Text);
            com.Parameters.AddWithValue("@Nationality", Nationalitydrp.SelectedItem);                
            com.Parameters.AddWithValue("@Pic", picpath.Text);
            com.Parameters.AddWithValue("@PassportPic", pppath.Text);
            //These are the relation between two tables
            com.Parameters.AddWithValue("@Emp_ID", "@ID");
            db.con.Open();
            int x = com.ExecuteNonQuery();
            db.con.Close();
            if (x > 0)
            {
                MessageBox.Show("Welcome " + Nametxt.Text + " in our organization" );

                nameerr.Visible = false;              
                nationalityerr.Visible = false;                   
                Nametxt.Text = null;
                Nationalitydrp.SelectedItem = null;                   
                picpath.Text = null;
                pppath.Text = null;


            }
    }

    }

The error pop up "error converting data type nvarchar to int" and it write data to Employee table only.

The DatePics.Emp_ID is the Foreign Key of the second table

Employee.ID is the Primary Key. It is suppose that there is one to one relationship between these tables. How to pass the auto generated value from Employee.ID to DatePics.Emp_ID in C# ?

Thanks

Answer 1

You have a couple of issues here.

First, you don't need this:

com.Parameters.AddWithValue("@Emp_ID", "@ID");

@Emp_ID is not a parameter in your stored procedure, and you don't need it to be, since employee id's are generated via identity (I'm assuming your id column in the Employee table is a PK identity column).

Second, in your stored procedure, you are not inserting the parent table id into the child table as the foreign key like you are intending; you're grabbing the id of the just-inserted employee and setting it to the @ID variable, but then you are inserting the (unpopulated) @Emp_ID variable as the foreign key in your child table. Do this instead:

ALTER PROCEDURE [dbo].[insert_emp_pics]
@EmpName nvarchar(100), 
@Nationality nvarchar(30), 
@PassportPic nvarchar(100), 
@Pic nvarchar(100)
AS
Begin
set nocount on;
DECLARE @ID int
insert into Employee (EmpName,Nationality)
values (@EmpName,@Nationality)
set @ID = SCOPE_IDENTITY(); -- This is the employee id that was just inserted
insert into DatePics 
(Emp_ID,PassportPic,Pic)
values
(@ID,@PassportPic ,@Pic) -- Use the just-inserted employee id to insert as a foreign key into the child table
set @ID_Pics  = SCOPE_IDENTITY();
 end

Answer 2

I don't think you have to pass @Emp_ID from your code,

ie try commenting out com.Parameters.AddWithValue("@Emp_ID", "@ID"); from your code.

Because you are inserting Emp_ID in DatePics table from @ID (declared in your stored proc.)

Also try to write the whole stored proc inside Transaction scope.